Polymeric materials, such as wet strength agents, are often added to paper products at the time of manufacture. In the absence of polymeric materials such as wet strength agents, a paper product normally retains only 3 to 5 percent of its strength after being wetted with water. However, a paper product including wet strength agents generally retains at least 10 to 50 percent of its strength when wet. Such polymeric materials are useful in a wide variety of paper product applications including, but not limited to, paper towels, milk and juice cartons, paper bags, and liner board for corrugated containers.
Paper has traditionally been defined as a felted sheet formed on a fine screen from a water suspension of fibers. Current paper products generally conform to this definition except that most products also contain non-fibrous additives. Dry forming methods are also utilized for the manufacture of a few specialty paper products. Pulp is the fibrous raw material for papermaking, and it is typically cellulosic based material. The distinction between paper and paperboard is based on product thickness; for example, all sheets above 0.3 mm thickness may be classified as paperboard.
Because of increased commercial emphasis on developing paper products based on recovered cellulose, there is a growing interest in developing paper which is readily repulpable. Paper and paperboard waste materials are difficult to repulp in aqueous systems without special chemical treatment when they contain polymeric materials such as wet strength agents.
Improving the repulpability of paper products containing polymeric materials such as wet strength agents has generally been achieved by modifying the repulping conditions. Typically, these improved repulping processes result in formation of environmentally undesirable chlorine-containing degradation products, usage of strong oxidizing agents, or proceed very slowly. Therefore, there is a need for a coating composition that provides a coated paper product with improved repulpability properties. Furthermore, there is a need for a coated paper article and method of making such a coated paper article capable of being readily repulpable without requiring significant modifications to the repulpability process conditions.